Toasty Grilled Zucchini/Cheese Sandwiches

2 medium zucchini, sliced lengthwise into 1/4” thick planks Kosher salt, black pepper 8 thin slices sourdough bread, or your favorite 2 c. grated sharp cheddar cheese 2 thinly sliced medium tomatoes, lightly salted Mayo or Miracle whip 1. Heat…